In most cases, the procedure for color correcting intrinsic tooth staining resulting from developmental enamel hypoplasia or altered mineralization of the enamel structure is to bond layers of resin veneer to the tooth to mask the defective enamel. A particular type of enamel discoloration, namely fluorosis staining, has been treated in ways which are related to but not anticipatory of the instant invention. These treatments include: mechanically grinding or sanding the enamel away, chemically dissolving the enamel or, lastly, by the technique of bleaching with a solution containing concentrated hydrogen peroxide.
Mechanical means of enamel removal employ grinding or sanding in conjunction with rotary power tools to speed the process. While this method indeed removes enamel structure, there is little fine control over the spinning powered cutting instrument and often the enamel is removed in an uneven fashion. In addition, the slightest error with the powered hand tool can cause significant damage deep into the enamel structure. This purely mechanical method is quite time consuming and can cause patient discomfort due to friction heating of the hard tooth structure by the rotating device.
Bleaching techniques have shown to be extremely time consuming, requiring numerous patient visits, and giving unpredictable results. The process is also often used in combination with heating of the tooth which can be painful to the patient and difficult to adequately administer. In addition, the dental pulp (nerve of the tooth) can be damaged if heated excessively.
A purely chemical approach to tooth enamel dissolution for enamel removal requires the use of hydrochloric acid in a strong concentration of 18% to 36% in solution. This method requires the acid be in contact with the tooth up to 10 minutes and also there is no ability to localize the treatment to a particular area of the tooth. The prior art technique of bleaching had occasionally used hydrochloric acid as a component of the solution, or in a separate step to the procedure, but in all reported cases, the hydrochloric acid used as an etching agent only. Abrasion was to be avoided.
In summary, the problems with prior art methods of removing enamel are that; they are time consuming, cause patient discomfort, are inadequate for intrinsic staining other than fluorosis, lack the adequate control to localize the treatment to specific areas of the tooth, and are inherently unsafe because dangerous acidic solutions are of strong concentration and if used in combination with powered rotary hand tools could easily cause uncontrolled scattering of harmful acid covered particles.